Whenever I plug in the receiver of my Logitech Cordless Desktop LX 500 (keyboard & mouse), xfce4-power-manager shows a single "missing" icon next to the battery icon in my systray. Upower seems to correctly identify the keyboard (but not the mouse), power-manager shows it in its settings dialogue, but with all power related information missing (i.e. "0").

I collected a bit of information that might help to identify the problem:

Thanks for the icon patch! Separately from the icon: do you actually see any percentage information for your mouse battery reported by xfce4-power-manager in a tooltip (like it is for the laptop battery)? Is the power-manager using the percentage info for the mouse at all? (Maybe it's showing the percentage by "filling" the icon? -- but I can't tell right away if that's the case from looking at it)

EDIT: while we wait for the official package update, a xfce4-power-manager package with the patch that fixes the icon can be quickly installed from ppa:alexei.colin/upower